Kristen Stewart hates watching her sex scenes in the 'Twilight Saga: Breaking Dawn Part 2'.

The 22-year-old actress admitted she is embarrassed by her attempts at a "sexy face" during the romantic scenes with real life boyfriend Robert Pattinson.

She said: "It's nice to see your own reflection while your making 'shmexy' faces. It's absolutely absurd, I want to shoot myself."

Related: 'The Twilight Saga: Breaking Dawn - Part 2' premieres in LA

Kristen also revealed she found it easy to quit smoking because she was never addicted to nicotine.

She explained to chat show host Conan O'Brien: "I was a bit of a faker, a circumstantial smoker. I just feel like I wasn't addicted to nicotine. I just wanted something in my mouth."

Meanwhile, Kristen said starring in the 'Twilight Saga' film franchise was a "once in a lifetime" experience but she was not impressed with the contacts she had to wear when her character became a vampire in the final movie.

She said: "Those red contacts are awful - like, tunnel vision, wallpaper eyes. I think I've been sitting around for years watching everyone else do it. I've played [Bella] every step of the way as a human, so that final one made so much sense to me, I was raring to go."